This work presents the study of the relations between the ribeirinhos (people who live on the side of the brooks) and Passo Fundo Brook, considering the social environmental interests and conflicts. In presence of these aspects, the complex thought of Edgar Morin and the environmental ethics allow us to enlarge and recapture the view of systemic interconnections. The reflection about quotidian and social transformation systematize the (re)cognition of the interdependence between the ribeirinhos and the brook. The methodology used on this study represents a group of applied methodologies, in reason of the dynamics observed on this community and the initial difficulties of insertion as a resercher. The method of the oral story, trough observations and interviews made, enabled the comprehension of the processes involved on this dynamics, showing the environmental problematics concerning the pollution and degradation of the brook, direct relation with the social problematics. The comprehension of the ecological subject proposed by Isabel Cristina de Moura Carvalho was used to analyse the narratives of people interviewed. In addtion to that, the human ecology according to Maria José Araújo Lima, utilized as methodology, provided an environment of discussions and interaction, developing a systemic vision for the problems observed. Considering this, the interaction between the ribeirinhos and the brook is also a result of a social-economic-historical context. The data reveal as the main pollution agent the population itself, through domestic dump, deforestation of ciliar forests and unappropriated invasion on the brookside, followed by chemical dumps deriving from industries and agriculture activity. We notice, then, the reduction of the biological diversity of the fauna and flora from this environment in direction to the estuary, flowing into Guaíba Lake. The social environmental relation observed shows as decisive factor of this process the manner how the population notices and integrates into the brook. Based on this, the healthy conviviality with this environment implicates ethical autonomy, reflective and active component, which guides to a complex view of interdependence in benefit to the improvement of life quality of these citizens and their brook.